1. Field of the Invention
The present invention relates to a process for the simultaneous production of bipolar and complementary MOS transistors on a common substrate which involves providing n-doped zones in a p-doped silicon substrate together with insulated npn bipolar transistors, where the n-doped zones form the collector of the transistor and the n-zones are superimposed over buried n.sup.+ -doped zones which are connected in the bipolar transistor zones by deeply extending collector terminals.
2. Description of the Prior Art
A process for forming 1.0 micron well CMOS bipolar transistors for highly integrated circuits is disclosed, for example, in an article by Miyamoto et al in the IEDM 1983, Technical Digest (December 1983), pages 63 to 66. In order to reduce the collector resistance, a buried collector is used which is connected by means of a deep collector contact.
The production of bipolar transistors having a buried collector and self-aligned base-emitter zones wherein the emitter and base zones are formed by diffusing-out of doped polysilicon structures is disclosed in an article by H. Murrmann entitled "Modern Bipolar Technology for High Performance ICs" in the Siemens Research and Development Reports, Vol. 5 (1976), No. 6, pages 353 to 359 and in an article by A. Wieder entitled "Self-Aligned Bipolar Technology--New Chances For Very High Speed Digital Integrated Circuits" in the Siemans Research and Development Reports, Vol. 13 (1984) on pages 246 to 252. Transistors of this kind are used in LSI circuits for high switching speeds.